The U.S. National Hurricane Center has downgraded tropical storm Dean to a tropical depression.

The storm has been weakening ever since it came ashore Wednesday near the city of Veracruz, carrying winds of 140 kilometers per hour. It made landfall as a Category 2 hurricane on the five-point scale that measures a hurricane's power and potential destructiveness.

Forecasters say the winds of Dean have decreased to just 55 kilometers an hour, and expect it to dissipate later Thursday over the mountains of central Mexico. But the storm is still expected to produce anywhere from 12 to 25 centimeters of rain, triggering life-threatening flash floods and mudslides.

Dean first struck Mexico's Yucatan Peninsula Tuesday as a Category 5 hurricane, with winds of up to 265 kilometers an hour.

Dean was the strongest Atlantic storm to hit land since 1988.

Mexican officials said they had evacuated thousands of residents from coastal areas to schools, churches and other buildings, while tens of thousands of oil workers also left the region.

Dean passed to the south of the popular resort destinations of Cancun and Cozumel, sparing that area from the worst wind and waves. The storm slammed into the coast of Mexico and Belize after pounding the Caribbean, where it is blamed for at least 18 deaths.

The U.S. Agency for International Development says it has provided more than $500,000 to Jamaica for emergency needs, and the Pan-American Health Organization is to receive $150,000 for aid efforts.